Regulation of Epidermal Growth Factor Receptor Cell Signaling and Endocytosis during Mitosis

Abstract

EGFR-mediated signaling has been studied extensively since the 1980s due to its importance in several types of cancers. The majority of the research however has focused on the actions of the EGFR during G0/G1 and has neglected to characterize EGFR outside of this cell cycle phase. In this thesis, I characterized EGFR signaling and endocytosis during the other phases of the cell cycle, mostly during mitosis. I characterized the differential regulation of various EGFR-mediated signaling pathways during mitosis, including the mechanism of ERK inhibition during mitosis. In addition, I showed that EGFR endocytosis during mitosis proceeds exclusively by non-clathrin mediated endocytosis, since EGFR endocytosis during mitosis is unaffected by clathrin knockdown and is much more dependent on the E3 ligase CBL than during interphase. Finally, I assayed for differences in the activation of EGFR and EGFR-mediated pathways during the various cell cycle phases, specifically during G1, S, G2, prometaphase, metaphase, and anaphase/telophase. My work has contributed to a fuller understanding of EGFR signaling and endocytosis, which will be important, for example, to better understand modulations to the EGFR for pharmacological purposes.